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Versions: 00 01 02 03 04 RFC 4908

No Specific Working Group                                      K. Nagami
Internet-Draft                                             INTEC NetCore
Expires: November 16, 2007                                        S. Uda
                                                             N. Ogashiwa
                                                           INTEC NetCore
                                                                H. Esaki
                                                                U. Tokyo
                                                             R. Wakikawa
                                                         Keio University
                                                              H. Ohnishi
                                                            May 15, 2007

  Multi-homing for small scale fixed network Using Mobile IP and NEMO

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   Copyright (C) The IETF Trust (2007).

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Internet-Draft        Multihoming for Fixed Network             May 2007


   Multi-homing technology improves the availability of host and network
   connectivity.  Since the node and network behavior of mobile
   networking and fixed networking are different, the different
   architecture has been discussed and proposed.  This document proposes
   the common architecture both for mobile and fixed networking
   environment, using the mobile IP [1] and NEMO [2].  The proposed
   architecture only requires a modification of the mobile IP and NEMO
   so that multiple-CoA can be used.  In addition, multiple HAs which
   are located in different place, are required for redundancy.

1.  Motivation

   Users of small-scale network need to improve the network availability
   and to get load balance of several links by easy method.  Multi-
   homing technology is one of solutions to improve the availability.
   Conventional major multi-homing network uses BGP.  But it has some
   issues.  Therefore, we propose a multi-homing architecture using the
   mobile IP and NEMO for small-scale fixed network.

1.1.  General Benefits of Multi-homing

   In a multi-homing network environment, both users and network
   managers takes several benefits by controlling out-going traffic, in-
   comming traffic or both of them.  Those benefits are listed in the
   draft [3] as the goals and benefits of multi-homing.  The following
   is a summary of those goals and benefits listed in the draft.

   o  Ubiquitous Access

   o  Redundancy/Fault-Recovery

   o  Load Sharing

   o  Load Balancing

   o  Bi-casting

   o  Preference Settings

1.2.  Problems to be Solved to Accomplish Multi-homing

   Several multi-homing technologies have been proposed so far.
   Conventional major multi-homing network uses BGP.  But it has some
   issues as follows.

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   (1) Increasing route entries in the Internet

      In the multi-homing environments, each user's network needs to
      advertise its address block to all ISPs connected to them.  If
      multi-homed user connects only one ISP, the ISP can advertise
      routing information to aggregate them.  But some multi-homed user
      needs to connect with different ISPs in preparation for failure of
      ISP.  In this case, ISPs need to advertise routing information for
      multi-homed user without aggregation.  Therefore, the number of
      routing entries in the Internet is increasing one by one.

   (2) Difficulty to efficiently use multiple links

      It is not easy to control in-coming traffics in the case of the
      conventional multi-homing architecture using BGP.  Therefore, load
      balancing of connected links is difficult.

1.3.  Using the Architecture of Mobile IP and NEMO to Solve the Problems

   Basically, the Mobile IP and the NEMO have been proposed for mobile
   host or mobile network, however the architecture and the protocol of
   them can be used for fixed networks.  The following problems
   mentioned avobe can be solved by using the architecture and the
   protocol of them.  The details of the solution is being described in
   the later section.

   o  increasing route entries in the Internet

   o  difficulty to efficient use multiple links

   Moreover, by using the architecture and the protocol of the MIP and
   the NEMO, a cost of network operation will be decreased.  For
   instance, in the architecture of the MIP and the NEMO, renumbering IP
   addresses when relocation of an office or network equipments becomes
   needless in consequence of that the network address prefix used in a
   user network in a Mobile IP environment is not depend on the upstream
   ISP's network prefix.

2.  Multi-homing Architecture Using Mobile IP and NEMO

2.1.  Mobile Network Includes Fixed Network

   NEMO and Mobile IP must work with multi-homing by its nature.  This
   is because mobile nodes need to use multiple links for improving the
   availability of network connectivity since the wireless link is not
   always stable.  Therefore, we propose that multihoming for fixed
   nodes (routers and hosts) use the framework of NEMO and Mobile IP.

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2.2.  Overview multi-homing network architecture using Mobile IP

   Figure 1 shows basic multi-homing network architecture.  In this
   architecture, a mobile router (MR), which is boarder router of multi-
   homed network, sets up several tunnels between the MR and the HA by
   multiple-CoA registration.  A HA or a router which the HA belongs
   advertise user's network prefix (Prefix X in Fig.1) to ISPs via
   routing protocol.  If HA has several multi-homed network (Prefix X
   and Y in Fig.1), they can advertise an aggregated network prefix to
   ISPs.  Therefore, the Internet routing entries do not increase one by
   one when multi-homed user is increased.

                                 ||(Advertise aggregated prefix X and Y)
        |                   The Internet               |
          |          |                    |          |
        ISP-A      ISP-B               ISP-A'      ISP-B'
          |          |                    |          |
          |          |                    |          |
          +--- MR ---+                    +--- MR ---+
          CoA1 | CoA2                      CoA1|CoA2
               |                               |
        -------+--------- (Prefix X)    -------+------ (Prefix Y)
        Multihomed Network X            Multihomed Network Y

              Figure 1: advertisement of aggregated prefixes

   Packets to multi-homed users go to HA and the HA sends packets to MR
   using CoA1 and CoA2.  The HA selects a route which CoA is used.  The
   route selection algorithm is out of scope of this document.  This can
   improve availability of user network and control an in-coming traffic
   between ISP and MR.  In the basic architecture, HA1 is single point
   of failure.  In order to improve availability of user network,
   multiple HA is needed.  This is described in later section.

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                                ^ | |
       (1) Packets to prefix X  | | |  (2) HA forwards the packets
           are sent to HA       | | v      to CoA1 or CoA2
                          | The Internet |
                            |          |
                            |          | |(3) packets are forwarded over
                            |          | |    the MIP tunnel selected by
                            |          | v    the HA1
                          ISP-A      ISP-B
                            |          | |
                            |          | |
                            +--- MR ---+ v
                            CoA1 | CoA2
                          -------+--------- (Prefix X)
                         Multihomed Network A

                     Figure 2: packet forwarding by HA

3.  Requirements for Mobile IP and NEMO

3.1.  Multiple Care-of-Addresses (CoA)

   Multiple Care-of-Addresses needs to improve the availability and to
   control in coming and out going traffic.  The current Mobile IPv6 and
   the NEMO Basic Support protocol does not allow to register more than
   one care-of address bound to a home address to the home agent.
   Therefore, [4] is proposed to extend the MIP6 and the NEMO Basic
   Support to allow multiple care-of address registrations for the
   particular Home Address.

3.2.  Multiple Home Agents

   Multiple Home Agents should be geographically distributed across the
   Internet, for the improvement of service availability and for the
   load balancing of HA.  When all the networks that have HA advertise
   the same network prefix to their adjacent router/network, the traffic
   is automatically routed to the nearest Home Agent from the view point
   of routing protocol topology.  This operation has been already proven
   operational technology in the area of web server application, such as
   CDN (Contents Delivery Network), regarding IGP and EGP.

   In order to operate multiple HAs, all HAs must have the same
   information such as binding information.  This is the synchronization

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   of database among the HA.  The HAHA protocol [5] introduces the
   binding synchornozation among HAs.  This is the same architecture as
   I-BGP.  The database is synchronized by full-mesh topology.  In
   addition, in order to simplify operation of HA, the database is
   synchronized using star topology.  This is analogy with I-BGP route

                             HA1 ------ HA2
                              |          |
                            | The Internet |
                              |          |
                            ISP-A      ISP-B
                              |          |
                              |          |
                              +--- MR ---+
                              CoA1 | CoA2
                            Multihomed Network

                 Figure 3: Architecture with HA redundancy

4.  Discussion on the Mailing List

4.1.  Why does the proposed architecture use NEMO protocols

   The multihome architecture proposed in this draft is basically same
   as the architecture of NEMO.  Furthermore, NEMO protocols meet to
   requirements of the proposed architecture in this draft, which are:

   o  protocol can inform CoA, HoA, BID from MR to HA

   o  protocol can establish multiple tunnels between MR and HA

   o  protocol support multiple HA and can synchronize Binding Caches
      among multiple HAs

   The proposed multihome architecture uses NEMO protocols as one of
   applications of NEMO.  Needless to say, using NEMO protocol is one of
   solutions to accomplish the proposed multihome architecture.  Another
   solution is to propose a new protocol just like NEMO.  Nevertheless,
   such new protocol will have functions just same as NEMO.

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4.2.  Route Announcement from Geographically Distributed Multiple HAs

   In proposed architecture, xSP (Multihome Service Provider) is
   introduced. xSP is a conceptual Service Provider and it doesn't have
   to be connected to the Internet physically for all practical purpose.
   xSP has one or more aggregatable mobile network prefixes. xSP
   contracts with some ISPs that are physically connected to the
   Internet.  The purpose of this contract is to setup some HAs into
   those ISP's network.  Those HAs announce the xSP's aggregated mobile
   network prefixes.  This means that HAs work just like border gateway
   router, and this situation is same as peering between ISP and xSP.
   In this case, origin AS announced from HAs is xSP.

   On the other hand, multihome user (small office user or home user)
   contract with xSP to acquire a mobile network prefix from xSP.  Each
   multihome user has a MR and multiple L3 connectivity to the Internet
   via multiple ISPs and the MR will establish multiple tunnels to HA.
   Since user's mobile network prefixes are aggregated and announced
   from HA, packets to user's mobile network will be sent to nearest HA
   depending on global route information at that time and HA that
   received such packets forward those packets to user's network over
   the established multiple tunnels.

   This model of route announcement from multiple HA is along with the
   conventional scalable Internet architecture and it doesn't have
   scalability problems.

5.  Implementation and Experimentation

   We have implemented and experimented the proposed architecture.
   Currently, the system works well not only on our test-bed network,
   but on the Internet.  In our experimentation, MR has two upstream
   organizations (ISPs) and two Care-of-Addresses for each
   organizations.  The MR uses multiple-CoA option to register the Care-
   of-Addresses to HA.

6.  Security considerations

   This document describes requirements of multiple CoAs and HAs for
   redundancy.  It is necessary to enhance the protocol of the MIP and
   the NEMO to solve the requirements.  Security considerations of these
   multihoming network must be considered in a specification of the each

7.  References

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7.1.  Normative References

   [1]  Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in
        IPv6", RFC 3775, June 2004.

   [2]  Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert,
        "Network Mobility (NEMO) Basic Support Protocol", RFC 3963,
        January 2005.

7.2.  Informative References

   [3]  Ernst, T., Montavont, N., Wakikawa, R., and E. Paik, "Goals and
        Benefits of Multihoming",
        draft-multihoming-generic-goals-and-benefits (work in progress),
        February 2004.

   [4]  Wakikawa, R., Ernst, T., and K. Nagami, "Multiple Care-of
        Addresses Registration", draft-ietf-monami6-multiplecoa-02 (work
        in progress), February 2007.

   [5]  Wakikawa, R., Thubert, P., and V. Devarapalli, "Inter Home
        Agents Protocol Specification",
        draft-wakikawa-mip6-nemo-haha-spec-01 (work in progress),
        March 2006.

Authors' Addresses

   Kenichi Nagami
   INTEC NetCore Inc.
   1-3-3, Shin-suna
   Koto-ku, Tokyo  135-0075

   Phone: +81-3-5565-5069
   Fax:   +81-3-5565-5094
   Email: nagami@inetcore.com

   Satoshi Uda
   Japan Advanced Institute of Science and Technology
   1-1 Asahidai
   Tatsunokuchi, Ishikawa  923-1292

   Email: zin@jaist.ac.jp

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   Nobuo Ogashiwa
   INTEC NetCore Inc.
   1-3-3, Shin-suna
   Koto-ku, Tokyo  135-0075

   Email: ogashiwa@inetcore.com

   Hiroshi Esaki
   The university of Tokyo
   7-3-1 Hongo
   Bunkyo-ku, Tokyo  113-8656

   Email: hiroshi@wide.ad.jp

   Ryuji Wakikawa
   Keio University
   Department of Environmental Information, Keio University.
   5322 Endo
   Fujisawa, Kanagawa  252-8520

   Phone: +81-466-49-1100
   Fax:   +81-466-49-1395
   Email: ryuji@sfc.wide.ad.jp
   URI:   http://www.wakikawa.org/

   Hiroyuki Ohnishi
   NTT Corporation
   9-11, Midori-Cho, 3-Chome
   Musashino-Shi, Tokyo  180-8585

   Email: ohnishi.hiroyuki@lab.ntt.co.jp

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